The term "electric components" is understood to include active electric components, such as integrated circuits, and passive electric components, such as ceramic substrates provided with electric contact blocks.
The invention is applicable, for example, to the hybridization of electronic components embodied on silicon substrates, and electronic components embodied on silicon or CdHgTe substrates.
There is already known to exist a first method to interconnect electric components, said method being diagrammatically illustrated on FIG. 1. According to this method, so as to interconnect two components 2 and 4, which respectively comprise a series of electric contact pads 6 and 8, each block of each series is provided with a soldering element 10, the two components are placed opposite each other and are accurately aligned with respect to each other so that each soldering element of one of the components is opposite the soldering element corresponding to the other component. Strong pressure is then exerted on the two components placed in contact so that the soldering elements, made of, for example, indium, yield and provide the electric link between the two components. So as to favor this yielding, it is preferable to soften the soldering elements to a temperature of possibly between 50.degree. C. and 80.degree. C. In addition, it is necessary to apply a force equal to at least 1 gram per pad, this force being applied homogenously on all the blocks so that the two interconnected components are able to bear the thermal and mechanical stresses which appear at the time they are used.
One example of such a method is described in the document (1) FR-A-2 569 052.
This first known method presents a certain number of drawbacks: the solidity of contact between the soldering elements is relatively average, despite the precautions taken as regards temperature and pressure when hybridizing components, this being expressed by the appearance of open contacts when these components are functioning. The number of points able to be hybridized is limited, especially owing to the fact that a force of 15 kilograms is required to hybridize a 128.times.128 point matrix, a force of 65 kilograms being required to hybridize a 256.times.256 point matrix. Currently, the applicable limit force using suitable available machines is equal to 15 kilograms. In addition, hybridization efficiency is relatively low with a defect rate of 10%; this efficiency is affected by a non-homogeneous pressure distribution concerning the soldering elements, this non-homogeneity being amplified by a parallelism defect between the components or by the surface unevenness of the latter, especially as regards large components. Finally, the alignment of the components needs to be extremely precise so as to have good hybridization efficiency.
There is also known to exist a second interconnection method described in the document (2), namely the article by J. MARSHALL and al., published in Solid State Technology, January 1979, p. 87 to 93.
According to this second method, the pads of the two components are initially provided with ball-shaped soldering elements for one of the components and with roughly flat-shaped soldering elements for the other component. The component bearing the pads covered with ball-shaped soldering elements is applied against the component to be connected to it, the latter component comprising pads provided with roughly flat soldering elements. This placing in contact of the components is effected so that each solder ball of one of the components is opposite the solder whose corresponding pad is provided on the other component. The assembly thus obtained is then heated to a temperature to melt the solder and is then cooled.
This second known method also has a certain number of drawbacks: it essentially is a complicated method requiring the prior embodiment of solder balls on one of the two components before interconnecting these two components. Furthermore, the solder is present on both components before the latter are interconnected.
The document (3) PCT/GB86/00538, (WO-A-8701509) describes a known third method to interconnect electric components.
This known third method also has a number of drawbacks:
It requires the production of special large pads for self-aligning when hybridizing electronic components, hence a significant active surface loss being limiting for high density connections (matrixes . . . ). PA1 Inherently in this third known method, the distance separating the two components is still smaller than the height of the smallest of the balls enabling these components to be interconnected, hence a limitation as regards withstand strength during thermal cycles (this withstand strength depending on the height of the ball in question). PA1 This third method does not make it possible to make up for any technological defects (non-conforming solder elements, for example). PA1 This third method does not make it possible to compensate any errors due to a bulgy shape of certain components (especially in the case of hybridizing large components, wafer/wafer, for example). PA1 the first and second components are placed in contact so that the soldering elements or wafers of the first component totally or partly cover the corresponding pads of the second component, PA1 the assembly of the first and second components thus obtained is heated to a temperature enabling the metallic material of the soldering elements or wafers to be melted, one of the first and second components being maintained whereas the other is free, and PA1 the temperature of the assembly is reduced below the melting temperature of the metallic material. PA1 procuring means in the first and second components in which the electrically conductive soldering elements or wafers cover the pads of components whilst projecting onto the environment of these blocks, these components provided soldering elements or wafers being selected so that it has one single wafer for each pair of the pads to be interconnected, these wafers being made of a metallic material with a low melting point and able to be soldered to the pads of the components, the latter being wettable by this material in the molten state, whereas their environment concerning the corresponding components is not wettable, PA1 means to receive interconnected components, PA1 means to align the components and provided to place in contact the soldering elements or wafers of each selected component with the pads of the component to be connected to this selected component, PA1 heating means provided to heat the assembly constituting the components placed in contact to a temperature able to melt the material, and PA1 means to transfer the components from the procuring means to the receiving means by passing through the alignment means and the heating means. PA1 optical means making it possible to observe the faces of components, namely the faces to be interconnected, and PA1 means for the relative displacement of these components.